A conventional torque wrench contains a rotatable controller for driving a screw rod of an extension of the torque wrench to rotate, and a sliding block screws with the screw rod and moves on the extension. When the sliding block is located at different positions, it forces a spring so as to adjust a torque value. However, after setting the torque value, the controller cannot be fixed, so the torque value is changed easily because the wrench vibrates or the controller is rotated unintentionally, such that when operating the torque wrench, the torque value cannot be marinated at a fixed value.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.